Understanding Feline Leukemia Virus (FeLV)

If your cat just tested positive for feline leukemia virus (FeLV), take a breath. Many cats with FeLV live comfortably for years with the right care. What matters most right now is understanding what you’re dealing with.

FeLV is a retrovirus that weakens the immune system over time. It’s one of the most common infectious diseases in cats, and one of the most preventable.

What is feline leukemia virus?

Feline leukemia virus is a retrovirus, meaning it works by inserting its genetic material directly into your cat’s cells. Once inside, it can interfere with how the immune system functions, how the body fights off infections, and in some cases, how normal cells divide. That last part is where the word “leukemia” comes in: FeLV can sometimes cause certain types of cancer, particularly affecting the blood and lymph nodes.

But not every cat with FeLV develops cancer, and not every cat deteriorates at the same pace. FeLV is different from feline leukemia the cancer. The virus can cause cancer, but it causes a lot of other problems too, mainly by suppressing the immune system, making it harder for the body to fight off infections it would normally handle without trouble.

How do cats get feline leukemia?

FeLV spreads through close, sustained contact between cats. The most common routes of transmission are:

• Saliva: Mutual grooming between cats is a major transmission route, as is sharing food and water bowls.
• Bites: A bite from an infected cat can pass the virus directly into the bloodstream.
• Mother to kitten: An FeLV-positive mother can pass the virus to kittens during pregnancy or nursing.
• Shared litter boxes: Less common, but possible since the virus can briefly survive in urine and feces.

FeLV does not spread through brief or casual contact, like two cats sniffing each other in passing. It requires the kind of close, repeated interaction that happens between cats who live together or spend extended time together outdoors. Indoor-only cats with no contact with other cats are at very low risk.

What are the first signs of feline leukemia?

Early FeLV symptoms are easy to miss because they look like a lot of other things. The first signs of feline leukemia often include:

• Low energy and lethargy
• Loss of appetite and weight loss
• Pale or yellowish gums (a sign of anemia, where the body isn’t producing enough healthy red blood cells)
• Recurring infections, like repeated respiratory illness or slow-healing wounds
• Swollen lymph nodes (the small glands under the jaw, behind the knees, or in the armpits)
• Diarrhea or other digestive issues

As the disease progresses, symptoms can include more significant weight loss, neurological changes like stumbling or altered behavior, and signs of secondary infections that a healthy immune system would normally handle. If your cat keeps getting sick, even with minor things, that pattern is worth raising with your vet.

How is feline leukemia diagnosed?

Diagnosis starts with a blood test. The most common screening tool is called an ELISA test (enzyme-linked immunosorbent assay), often run in-clinic using a SNAP test, a small rapid test that gives results in minutes. These tests detect a protein the virus releases into the bloodstream. If the SNAP test comes back positive, your vet will typically recommend a confirmatory test, usually an IFA (immunofluorescent antibody) test or PCR (polymerase chain reaction) test, to confirm the result and help determine how the infection is behaving in your cat’s body.

All cats should be tested when they’re first adopted, after any potential exposure to FeLV-positive cats, and as part of routine wellness care if they go outdoors or live with other cats.

Progressive vs. regressive infection: what the difference means for your cat

Not every cat who tests positive for FeLV ends up carrying the virus for life.

	Regressive infection	Progressive infection
What happens	Immune system partially controls the virus	Virus continues to replicate and spread
Testing	May test negative on follow-up ELISA tests	Remains consistently positive
Risk to other cats	Lower	Higher; should be kept separate from FeLV-negative cats
Long-term outlook	Often lives a normal lifespan	More likely to develop FeLV-related illness over time
Who’s most affected	Adult cats with healthy immune systems	Kittens and young cats

Your vet will use follow-up testing over a few months to help determine which pattern your cat is showing.

FeLV treatment and supportive care

There’s no cure for FeLV itself, but that doesn’t mean there’s nothing you can do. Treatment focuses on managing symptoms, preventing secondary infections, and keeping your cat as healthy and comfortable as possible. Your vet may recommend:

• Regular wellness visits (every six months rather than annually) to catch problems early
• Prompt treatment of any infections, since an FeLV-positive cat can’t fight them off as effectively
• A high-quality diet and keeping your cat indoors to reduce stress and exposure to other pathogens
• Antiviral medications in some cases, though these are used selectively
• Treatment for anemia if the virus is affecting red blood cell production
• Chemotherapy or other cancer-directed treatment if FeLV has led to lymphoma or another cancer

How long can a cat live with feline leukemia? It varies a lot. Cats with regressive infections often live completely normal lifespans. Cats with progressive infections have a more guarded outlook, but many still live two to three years or more with consistent supportive care. The quality of that time matters as much as the quantity.

FeLV vs. FIV: two retroviruses people often mix up

FeLV and FIV (feline immunodeficiency virus) are both retroviruses that affect cats’ immune systems, and they get confused constantly. They are genuinely different diseases.

	FeLV	FIV
How it spreads	Saliva, grooming, shared bowls	Almost exclusively through deep bite wounds
Most common in	Any cat with close contact with infected cats	Outdoor male cats who fight
Casual contact risk	Higher	Very low
Progression	Tends to progress faster, especially in young cats	FIV-positive cats often live into old age with proper care
Vaccine available?	Yes, highly effective	No vaccine available in the U.S.

If your cat was just diagnosed with one of these, make sure you know which one. The management strategies and what to expect are meaningfully different.

Preventing FeLV: the vaccine and testing new cats

The feline leukemia vaccine is one of the most effective tools available. It’s recommended for all kittens and for adult cats with any outdoor access or exposure to other cats. It’s considered a “lifestyle vaccine,” meaning your vet will factor in your cat’s specific risk level when deciding whether to continue it annually after the initial series.

If you’re bringing a new cat into a home with existing cats, test the new cat for FeLV before introducing them, even if the new cat appears healthy. Cats can carry and shed the virus without showing any symptoms at all.

Does pet insurance cover feline leukemia?

The ongoing care, testing, and treatment for FeLV-positive cats adds up fast. Lemonade Pet covers illness, including the kind of supportive care and diagnostics that FeLV-positive cats often need, as long as the condition isn’t pre-existing and develops after the 14-day illness waiting period has passed.

If your cat hasn’t been diagnosed yet, or you have a new cat you’re about to test, now is the right time to get a quote. Getting coverage while your cat is healthy means you’re actually protected when something comes up.

Before we go

A positive FeLV test is heavy news, but it’s not the end of the story. With the right care, regular vet visits, and a protected indoor environment, FeLV-positive cats can still have a genuinely good quality of life. Stay close with your vet, watch for recurring illness, and don’t let minor symptoms go uninvestigated.

A few quick words, because we <3 our lawyers: This post is general in nature, and any statement in it doesn’t alter the terms, conditions, exclusions, or limitations of the policies issued, which differ according to your state of residence. You’re encouraged to discuss your specific circumstances with your own professional advisors. The purpose of this post is merely to provide you with info and insights you can use to make such discussions more productive! Naturally, all comments by, or references to, third parties represent their own views, and Lemonade assumes no responsibility for them. Coverage may not be available in all states. Please note that statements about coverages, policy management, claims processes, Giveback, and customer support apply to policies underwritten by Lemonade Insurance Company or Metromile Insurance Company, a Lemonade company, sold by Lemonade Insurance Agency, LLC.  The statements do not apply to policies underwritten by other carriers.